Fix Paystack, Integrate MPesa Rapidly

I have an active code-base that suddenly began rejecting live payments through Paystack. I need the fault isolated and patched, then I want MPesa (Daraja/Safaricom) added as a second gateway—all inside a tight 5-hour window from the moment we start a screen-share session... (Budget: $15 - $25 USD, Jobs: Debugging, Full Stack Development, JavaScript, MySQL, Node.js, Payment Gateway Integration, REST API, Software Development)